1. Field of the Invention
The present invention relates to a display device, and more particularly, to a display device with a flexible display panel and a method for controlling the same.
2. Description of the Related Art
In general, a display device displays information and controls the operation states of its device, such as a TV in a home, electronic products, a car, mechanical equipment, etc.
Along with the increasing popularity of mobile communication service, display devices for portable terminals have been drastically evolved. In its early development stage of the mobile application, the display device merely displayed simple characters. Now, its technology has advanced remarkably enough to display high-definition pictures or videos.
Due to the requirement of portability, the portable terminal needs to be compact and lightweight. As multimedia service is now readily available, the display devices of the portable terminals tend to be larger. However, there are restrictions on extending a display device, while maintaining a portable terminal compact and lightweight. As the display device area is made larger, efforts have been made mainly on a reduction of the thickness of the portable terminal with an incorporation of a touch screen, instead of a physical keypad.
Since a virtual keypad can be configured on a screen, a touch screen display device can eliminate the physical keypad from the portable terminal. Accordingly, a portable terminal equipped with a touch screen display device can offer a larger screen than a general portable terminal without it. Thus, the portable terminal having a touch screen display device is more favorable.
Recently, a technology for bending or folding a display device by fabricating the display device with a flexible display panel has been proposed. As the larger display device can be bent or folded, the portability of a portable terminal such as a mobile communication terminal can be enhanced. For example, a flexible display device is disclosed in Korea Patent Publication No. 2009-87303 (published on Aug. 17, 2009).
FIG. 1 illustrates a folded flexible display panel in a conventional display device. As shown, in a state where the flexible display panel is bent or folded, tensile force is applied to the outer surface of the flexible display panel, thus causing cracks on the outer surface of the flexible display panel. In addition, as the flexible display panel is bent or folded repeatedly, tensile load is also repeatedly applied on the outer surface of the flexible display panel. As a result, even though cracks are not produced, the flexible display panel is vulnerable to permanent deformation. However, permanent deformation or cracks of the flexible display panel may not be perceivable or visible to a user. As such, after damage or deformation, its cause cannot be analyzed during normal operation until it's too late.